The Crystal of Cantus was the twenty-eighth Bernice Summerfield audio story released by Big Finish Productions. It was the fifth and final story of the sixth season. It was told unconventionally through voice-overs and flashback-style point of view scenes.

This story also featured the Cybermen, as the cover art (and dialogue in-story) indicates Cybermen of The Tomb of the Cybermen-era. It is notable for its gruesome revelation of how the Cybermen create Cybermats: from babies.

Contents

Fabled crystals from long-dead civilisations. Jason Kane blundering into situations out of his control. Entombed Cybermen waking from a century-long sleep. It's all in a day's work for Professor Bernice Summerfield. Armed with her endless supply of witty quips and penchant for alcoholic beverages, she'll find the Crystal, rescue Jason, destroy the Cybermen and be home in time for supper.

Except, this time, it's different. This time, as the saying goes, it's personal.

Benny corrects Parasiel in that the Cybermen came originally from Mondas, not Telos. She gives a potted history of the origins of the Cybermen: they were dying and started replacing their parts (TV: The Tenth Planet ; AUDIO: Spare Parts)